Fram R J, Woda B A, Wilson J M, Robichaud N
Department of Medicine, University of Massachusetts Medical School, Worcester 01655.
Cancer Res. 1990 Jan 1;50(1):72-7.
To study mechanisms underlying resistance to cis-diamminedichloroplatinum (II) (cis-DDP) we have induced resistance to this agent in BE human colon carcinoma cells. A 5-fold increase in the IC50 of resistant compared to sensitive cells was noted as analyzed by the inhibition of cellular growth. Up to a 4-fold reduction in interstrand cross-link formation by cis-DDP in resistant compared to sensitive cells was present as measured by alkaline elution. No significant differences were detectable either in the extent of DNA platination as analyzed by atomic absorption spectroscopy or in the induction of cis-DDP DNA adducts as evaluated by an enzyme-linked immunosorbent assay employing antiserum that detects intrastrand cross-links formed by cis-DDP. Further, no differences in the kinetics of excision of DNA interstrand cross-links, cis-DDP DNA adducts, or total platinum in DNA were present. Levels of glutathione, however, were increased about threefold in resistant compared to sensitive cells. Loss of resistance was associated with increased interstrand cross-link formation and declines in glutathione levels. Our results are consistent with a critical role of glutathione in preventing platinum monoadduct rearrangements resulting in lower levels of interstrand cross-links and resistance to cis-DDP in resistant BE cells.
为了研究顺二氯二氨铂（II）（顺铂）耐药的潜在机制，我们在BE人结肠癌细胞中诱导了对该药物的耐药性。通过细胞生长抑制分析发现，与敏感细胞相比，耐药细胞的半数抑制浓度（IC50）增加了5倍。通过碱性洗脱法测定，与敏感细胞相比，耐药细胞中顺铂诱导的链间交联形成减少了4倍。通过原子吸收光谱分析的DNA铂化程度，或通过使用检测顺铂形成的链内交联的抗血清的酶联免疫吸附测定评估的顺铂DNA加合物诱导情况，均未检测到显著差异。此外，DNA链间交联、顺铂DNA加合物或DNA中总铂的切除动力学也没有差异。然而，与敏感细胞相比，耐药细胞中的谷胱甘肽水平增加了约三倍。耐药性的丧失与链间交联形成增加和谷胱甘肽水平下降有关。我们的结果表明，谷胱甘肽在防止铂单加合物重排中起关键作用，从而导致耐药BE细胞中链间交联水平降低和顺铂耐药。
